Kevin Durant became the first NBA star to sign with Jay-Z’s Roc Nation agency. Durant posted a photo on social media Monday of himself and the rap mogul with the paperwork. Jay-Z became certified as a representative by the NBA players’ association last week. A quote attributed to Durant above the picture says he’s “grateful for this opportunity with Roc Nation Sports. It’s go time.” The Oklahoma City star and Olympic gold medalist — who had a field-goal percentage over 50, a 3-point percentage over 40 and a free-throw percentage over 90 — left agent Rob Pelinka to sign with Roc Nation.